I don’t disagree with your broader definition of “accessibility” as a concept, and Apple making their consumer devices more accessible is fine. The core issue for me (and perhaps some others), and the reason I choose to make the distinction between purpose built assistive devices and general consumer products, is the trust factor.
As I understand it (and I’m no expert) such devices are produced to solve specific problems on behalf of those with applicable conditions/challenges. They are designed from the ground up with that purpose as the primary requirement, and (in the US) they have to meet strict requirements for privacy and security. It is understood they are produced in relatively low numbers, which combined with the requirements they have to meet, makes the devices expensive.
Given where we are with technology today, I have zero reason to trust the companies making general consumer tech products will continue to respect my privacy as a user, or that of those around me if they see a way to make a buck out of it. All they have to do os change the EULA, which they warned us from the start they could change. To me, claims that a device someone is wearing will not allow the user to take pictures or video mean nothing if it is still feeding an AI back end with data about me or my surroundings.